The present invention relates to a communications system, and more particularly to a communications system for transmitting and receiving remote control messages to control electronic devices.
A variety of remote control systems that transmit and receive remote control messages to control various electronic devices are known. Such systems typically include a remote control device which comprises an input device, such as a keypad, for allowing user input, coupled to a controller which is in turn coupled to a signal transmitter. In response to a user input, the controller generates an appropriate remote control message using look up tables, and the like, from memory and causes a signal transmitter to transmit the remote control message. The signal transmitter may be designed to transmit the remote control message in a number of different forms, including, but not limited to, an IR signal and a RF signal.
One commonly used method of sending a remote control message is to transmit the message in IR signal form. Remote control devices that transmit IR signals are well known and commonly used with household electronic devices. The message format of the IR signal is determined by the manufacturer for each model and many such IR message formats are known and used. Each format specifies a set of message characteristics, which include, but are not limited to message duration, transmission and pause intervals and types of data carried in the remote control message.
However, there are several disadvantages associated with using IR signals to control an electronic device. First, the IR signal is directional and as such requires the user to point the remote control device toward the destination device for proper transmission performance. Also, the IR signal may have a relatively short range and be easily blocked by objects such as walls, floors, ceiling and the like, so a remote control device must generally be used in the same room in which the destination device is located.
Also, many existing IR signal message formats do not have sufficient data carrying capacity to transmit all of the different types of remote control data required for controlling many modern electronic devices. For example, in addition to the conventional remote control messages associated with household electronic devices, such as ON, OFF, Channel Up, Channel Down, etc., many modern electronic devices, such as satellite receivers, may require the remote control device to send other forms of data, such as ASCII character data. Many existing IR signal message formats are not designed to handle such additional forms of data and/or simply do not include enough capacity to carry the data.
Another method of sending a remote control message is to transmit the message in RF signal form. RF signals are generally non-directional and have greater range than IR signals. RF signals may also be transmitted through objects such as walls, and the like, so that the user can use the remote control device to control a device in a separate room. This extended range and ability to transmit messages through objects is beneficial in situations where a central device, such as a set top box or a satellite receiver, provides input to a plurality of devices located throughout different rooms in a building. Also, RF signal message formats generally have wider bandwidths, and thus have greater data carrying capacity, than existing IR signal formats.
As such, it is desirable to be able to use RF signals to control modern electronic devices. However, devices and methods using IR signals remain popular and are widely used. In order to maintain backward compatibility, i.e., allow a remote control device to control existing devices which utilize IR signals, a remote control device should also be capable of transmitting IR signals. Therefore, it is desirable to have an apparatus and a method for easily and efficiently transmitting some combination of IR and RF signals to take advantage of the features of the two signal transmission forms.
However, existing IR signal message formats, or protocols, are not totally suitable for transmitting remote control messages in RF form. Since, the RF signals have longer range and transmit through objects better than IR signals, a RF signal message format must include a method of preventing interference from neighboring RF signal transmitters. Also, existing IR signal message formats do not allow a remote control device to send different types of data, such as ASCII data, in addition to the standard IR signal commands. Further, existing IR signal message formats do not take full advantage of the increased bandwidth and expandability associated with RF signals. Limited use of the available bandwidth and limited expandability reduces the ability to efficiently transmit and receive additional data, as well as more complex data, thereby limiting the ability to add new types of remote control devices to an existing system and incorporate new features to existing remote control devices.
Therefore, what is needed is a communications system for use in a remote control system which provides for increased data carrying capacity and expandability. In particular, what is needed is a communications system which uses a message protocol that provides for the ability to efficiently transmit and receive an increased amount of data, as well as different types of data, compared to existing remote control message protocols. Further, what is required is a message protocol which can be expanded to carry an additional amount of data and/or more types of data, yet remain both forward and backward compatible with existing and future receiver/decoders.
The present invention involves a communications system that uses a message protocol which provides for the transmission and receipt of complex data, as well as different types of data, such as ASCII data, and allows for expansion of the message as required, in an efficient format. The present communications system and message protocol is suitable for transmitting and receiving remote control messages in RF signal form, and especially suitable for transmitting and receiving a RF signal in combination with an IR signal by time multiplexing the two signals.
In accordance with one aspect of the present invention a remote control apparatus is provided, comprising an input device for receiving remote control messages from a user, a signal transmitter, and a controller operatively coupled to the input device and the signal transmitter, the controller generating a remote control message and causing the signal transmitter to transmit the remote control message in response to the user input, the remote control message comprising a plurality of data fields, each of the data field ending with an end of field marker, the plurality of data fields comprising a status field having signal transmission information including a keycode type bit, and a keycode field having one of first and second data in accordance with a state of the keycode type bit.
In accordance with another aspect of the present invention, a remote control system is provided, comprising an input device for receiving remote control messages from a user, an IR signal transmitter, a RF signal transmitter and a controller operatively coupled to the input device, the IR signal transmitter and the RF signal transmitter, the controller generating an IR remote control message and a RF remote control message and causing the IR signal transmitter and the RF remote signal transmitter to transmit the IR and RF remote control messages, respectively, in a time multiplexed manner in response to the user input, the RF remote control message comprising a plurality of data fields, each of the data fields ending with an end of field marker, the plurality of data fields comprising a status field having signal transmission information including a keycode type bit, and a keycode field having one of first and second data in accordance with a state of the keycode type bit.
In accordance with another aspect of the present invention, a remote control apparatus is provided comprising an input device for receiving remote control messages from a user, a signal transmitter, and a controller operatively coupled to the input device and the signal transmitter, the controller generating a remote control message and causing the signal transmitter to transmit the remote control message in response to the user input, the remote control message comprising a start sequence comprising a pulse and pause period having about equal duration, a preamble field having data for addressing a destination device, a security code field having an identifier associated with said signal transmitter, a status field having signal transmission status information, a keycode field having either a first or second data in accordance with a keycode type bit in the status field, a checksum field for verifying transmission integrity of the remote control message and an end of message marker.
In accordance with another aspect of the present invention, a remote control apparatus is provided comprising a signal receiver adapted to receive a remote control message, a controller operatively coupled with the signal receiver, the controller adapted to decode and process the remote control message, the remote control message comprising a plurality of data fields, each of the data fields ending with an end of field marker, the plurality of data fields comprising a status field having signal transmission information including a keycode type bit, and a keycode field having one of first and second data in accordance with a state of the keycode type bit.
In accordance with another aspect of the present invention, a method of transmitting a remote control message is provided comprising the steps of: receiving a user input; generating a remote control message corresponding to the user input, the remote control message comprising a start sequence followed by a plurality of data fields and an end of message marker, each of the data fields ending with an end of field marker, the plurality of data fields comprising a preamble field having data for addressing a destination device, a security code field having an identifier associated with the remote control apparatus, a status field having transmission status information about the remote control message, a keycode field having data associated with the user input and a checksum field for verifying transmission integrity of the remote control message; and applying the remote control message to a signal transmission circuit.